TOXOPLASMA: A FETAL AND SOMETIMES FATAL PARASITE

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TOXOPLASMA A FETAL AND SOMETIMES FATAL PARASITE

• Angel Criado
• Laboratorio de parasitología
• Facultad de Farmacia - Universidad de Alcalá de
  Henares (Madrid) - Spain.

• Sources of general information on parasites
• Dpdx.Cdc.Parasite diagnostic web site
• Lib.Uiowa.Edu/hardin/
• Dspace.Dial.Pipex.Com/

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Why should I mind for this almost unknown
parasite ?

• Only in the USA, the sanitary cost of raising
  transplacentally infected children was 5.3
  billion (1993).
• An important percentage of AIDS patients die
  because of toxoplasmosis.
• The fetal infection can be also of veterinary
  importance, sheeps and goats are prone to
  abortion due to Toxoplasma.

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LEARNING OBJECTIVES

• UNDERSTANDING PARASITE BIOLOGY/TRANSMISSION
• RECOGNIZING THE MAIN EPIDEMIOLOGIC FEATURES OF
  THE DISEASE
• REALIZING THE IMPORTANCE OF PREVENTIVE ACTIONS

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TOXOPLASMA ID CARD

• Toxoplasma is an Apicomplexan protozoa
• It is an intracellular pathogen
• Man, mammals and birds are adecuate hosts for the
  parasite
• In the fetal life, the parasite infection can
  lead to death (man, sheep)

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EPIDEMIOLOGICAL FEATURES OF TOXOPLASMOSIS

• In places where raw meat consumption is usual,
  population shows high prevalence of toxoplasmosis
  
• Children between 0- 4 years do not usually eat
  raw meat, so that if toxoplasmosis prevalence in
  children populatoin is high, contamination from
  cats is the suspected source of infection

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SOME CURIOSITIES ON HUMAN TOXOPLASMOSIS

• Toxoplasma oocysts can be infective by inhalation
• This is likely to happen in places where vegetal
  ceilings/roofs/false atics are used in house
  building
• Cat feces in the roofs/false atics are gradually
  degraded and oocysts can go down through the
  vegetal building material
• Inhalation of dust particles (oocysts
  included)can lead to infection

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SOME CURIOSITIES ON ANIMAL TOXOPLASMOSIS(I)
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SOME CURIOSITIES ON ANIMAL TOXOPLASMOSIS(II)
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SOME CURIOSITIES ON ANIMAL TOXOPLASMOSIS(III)
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SOME CURIOSITIES ON ANIMAL TOXOPLASMOSIS(IV)
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THE EPIDEMIOLOGY OF TOXOPLASMOSIS(I)

• After some slides concerning biology and
  transmission, we start now to see important
  features of Toxoplasma epidemiology
• This part of the lecture will be practical, so
  that you may have to answer some questions
  related to what we have explained up to now.
• Please go to the next slide.

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THE ANSWERIN SOUTH AMERICA PEOPLE GET INFECTED
EARLY IN LIFE BY OOCYST INGESTION.
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THE ANSWERXENOSMOPHILIA

• This is not the title of an horror film, is the
  dog habit causing an increase in the likelyhood
  of children becoming into contact with oocysts
  coming from cat feces.
• Dogs frequently eat and roll in cat feces, so
  that their fur is frequently impregnated with
  oocysts. Children desire contact with pets and
  dogs are more tolerant to petting that cats, so
  that infection from dog happens more easily than
  from cat.

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AND NOW A LITTLE BIT OF GEOGRAPHY

• To finish our overview of epidemiology of
  toxoplamosis, lets tell you two additional
  details
• Usually cold and dry climates are unfavourable
  for toxoplasmosis (oocysts are killed by low
  temperatures and sun exposure).
• Tropical or moist climates favours Toxoplasma
  survival

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WORLWIDE TOXOPLASMA I

• Answer- Compsumption of undercooked meat is
  particularly common in Paris

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REMIND SLIDE No. 8

• NO THERE ARENT SO MANY CATS IN THIS COUNTRY
• HIGH LEVEL OF INFECTION IS SUPPOSED TO BE CAUSED
  BY INHALATION OF OOCYSTS IN HOUSES BUILT WITH
  VEGETAL MATERIALS
• THIS HYPOTHESIS WAS POINTED OUT BY RUIZ
  FRENKEL, 1977, J. PARASITOL., 63 931-932.

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AUSTRALIA IS DIFFERENT

• Toxoplasma infection levels are low in kittens
  and Australian wildlife
• Its been suggested that humans are mainly
  infested by mutton ingestion (in any case low
  prevalence figures are frequent in Australia).
• It is possible that Toxoplasma transmission in
  marsupials is hampered because they die soon
  after infection, although this is just an
  unproven hypothesis.

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Toxoplasmosis preventive measures for pregnant
women (I)

• Always eat cooked or frozen meat
• Euthanasia of pets (cats/dogs) is essential
• Treat the family cat to avoid oocyst production
• Just treat undiscriminately pregnant women with
  several drugs
• Early diagnosis/treatment is very important
• Do not eat fruits/vegetables without boiling them

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Prevention Correct Answers (I)

• Correct measures freezing/cooking meat , Cat
  treatment (rarely used but possible -only for
  seronegative cats), early diagnosis and treatment
• Uncorrect killing pets, undiscriminate
  treatment, boiling vegetables

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Preventive measures for pregnant women (II)

• A prenuptial diagnosis test is advisable
• Avoid handling raw meat, particularly mucous
  membranes
• Medicine Doctors must advice women to become
  seropositive before pregnancy by eating raw meat
  or getting in contact with cat feces
• Use gloves when handling soil (gardening)
• Prevent access of cockroaches to food
• Wash hands after using toilets

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Prevention Correct Answers (II)

• There were two wrong prophylactic measures
  Unsanitary advices from Medicine Doctors and hand
  washing after using toilets.
• Particularly useful is the prenuptial
  toxoplasmosis test (it can be eventually
  postponed untill couple decides that family
  should increase in size, indeed!)

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FINAL REMARKS

• The idea of vaccination for toxoplasmosis (in
  sheep and cats) is under study.
• Some authors have found that latent Toxoplasma
  infection in children has a negative influence
  on mental health (slow learners, behavioural
  disorders...).